Hydraulic binders with short hardening time, such as dental MTA (Mineral Trioxide Aggregate) or industrial shotcrete may be useful depending on the fields. Among these, dental MTA has been introduced by Torabinejad et al. in the form of a mixture of Portland cement and a radiopaque material. In connection with the constitution of the MTA, reference can be made to US 2005/0263036 and U.S. Pat. No. 5,415,547 (the contents of which are incorporated herein in their entirety).
MTA is mainly used for root canal filling, pulp capping, and restoration of root perforation sites, for example. Portland cement, which is the main component of the MTA, includes tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate, tetracalcium aluminoferrite (C4AF) and the like. In the case of the MTA, calcium sulphate may be added to suppress the rapid hydration reaction of calcium aluminate in early stages.
Since the MTA acts on sites where body fluids, saliva and other liquids are present, it should be hardened stably and quickly to have hermeticity. However, unfortunately, the MTA made of conventional Portland cement has a long hardening time of about three hours, which results in insufficient washing resistance and poor workability.
Therefore, there has been introduced the MTA in which calcium chloride is added to Portland cement to reduce the hardening time to about 57 minutes. In connection with this, reference can be made to US 2007/0009858 (the contents of which are incorporated herein in their entirety). However, the above hardening time is also still long in clinical aspects. Particularly, in the case of tooth reimplantation whose procedure time should be shortened to 11 minutes or less, rapid hardening of the MTA becomes more important. Further, even in the case of daily dental pulp treatment such as direct pulp capping, a short hardening time of 10 minutes or less is desired because it is required to reduce the number of procedures so that the number of hospital visits can be reduced and the convenience in performing the procedures can be maximized.
Accordingly, the use of calcium aluminate can be considered. It is known that the addition of calcium aluminate at 40 to 60% of the weight of Portland cement can reduce the hardening time to about 15 minutes. In connection with this, reference can be made to US 2005/0263036 (the contents of which are incorporated herein in their entirety). However, when a large amount of calcium aluminate is added as above, the amount of calcium hydroxide produced from the MTA is reduced to hinder antibacterial effects and tissue regeneration effects caused by the calcium hydroxide.
Therefore, there is a need for a novel rapid-setting hydraulic binder composition that can achieve a short hardening time, hardening time control performance, hermeticity, antibacterial property and biocompatibility, without excessive addition of calcium aluminate.